A MEGACO protocol is a RFC3015 protocol of the Internet Engineering Task Force (IETF).
FIG. 1 is a schematic diagram of implementing system networking of the MEGACO protocol, in which the dot line represents a media stream. With an idea of adopting decomposed gateway, the MEGACO protocol decomposes original centralized processing gateway of signaling and media into two parts: media gateway (MG) and media gateway controller (MGC). The media gateway controller MGC controls media gateway (MG) action with a MEGACO protocol. When the media gateway controller (MGC) sends a command of performing to the media gateway (MG), the media gateway (MG) executes the command and then returns the result. The media gateway MG may also initiatively report observed events to the media gateway controller (MGC) for executing. A logical relation in MEGACO protocol is represented by a link model, and two essentially basic members in this link model are contexts and terminations, in which terminations are a logic entities of media gateway (MG) for sending and/or receiving one or multiple media streams, and contexts is a relationship of connection and topology among terminations.
Main commands between media gateway controller (MGC) and media gateway (MG) include SERVICECHANGE, ADD, MODIFY, SUBTRACT and NOTIFY commands, etc.
A signaling agent means that media gateway controllers (MGC) and media gateways (MG), in different networks and not being reachable to one another by routes, realize MEGACO signaling traversing and traversing media streams controlled by MEGACO signaling through networks through signaling agent, so as to make media gateway controllers enable to control media gateways (MG) in other networks completing call establishing and media streams intercommunicating between different networks.
Conventional methods for realizing signaling and media agent based on network address translation (NAT) can not implement entire transparence of agent equipments to media gateway controller (MGC), so that it can not implement direct control of media gateway controller (MGC) on media gateways (MG) in other networks not being reachable to one another by routes, thus the complexity of call services on media gateway controller is increased and meanwhile it needs to configure detailed information of corresponding media gateways (MG) on agent equipment. When a media gateway (MG) has changed, it needs to change configuration on both the media gateway controller (MGC) and the agent equipment simultaneously, and thereby operation maintenance cost is increased.